Alejandra, a manager, sends an e-mail warning Cameron, a sub…

Alejandra, a manager, sends an e-mail warning Cameron, a subordinate, of disciplinary action to be taken if he continues to spend too much time on personal phone calls. However, Cameron did not attach too much importance to the e-mail, thinking it was just a passing reminder. Which of the following is a reason why Alejandra should have spoken to Cameron directly and avoided the use of e-mail?